U.S. Pat. No. 5,700,867 relates to an aqueous polyurethane dispersion having an ionic functional group, polyoxyethylene units and hydrazine groups and used as a composition for ink, coating or adhesive. The polyoxyethylene units can be in the main chain, at the end of the main chain or in side chains of the aqueous polyurethane. The content of polyoxyethylene units is about 20% by weight or less of the weight of the resin. Desirable properties of the composition include storage stability, water resistance, pigment dispersibility, and adhesion. There is no teaching or suggestion regarding breathability properties of the composition or the importance of amounts and length of side-chain and main-chain polyoxyethylene in achieving both breathability and other suitable polyurethane properties.
U.S. Pat. No. 5,043,381 relates to an aqueous dispersion of a nonionic water-dispersible polyurethane having pendant polyoxyethylene chains and one crosslink per 3,000 to 100,000 atomic weight units. U.S. Pat. No. 4,992,507 relates to an aqueous dispersion of a nonionic, water-dispersible polyurethane having pendant polyoxyethylene chains and free acid or free tertiary amino groups. Diols and diisocyanates having pendant polyoxyethylene chains are mentioned generally in both of the latter two patents, such as those in U.S. Pat. Nos. 3,905,929 and 3,920,598 respectively. The dispersions are useful as coating compositions, but there is no teaching or suggestion in any of the latter four references regarding breathability properties of the compositions or the importance of amounts and length of side-chain and main-chain polyoxyethylene in achieving both breathability and other suitable polyurethane properties.
U.S. Pat. No. 4,983,662 relates to an aqueous selfcrosslinkable coating composition comprising an aqueous dispersion of at least one polyurethane and having hydrazine (or hydrazone) functional groups and carbonyl functional groups disposed therein to provide a selfcrosslinkable reaction, in which the polyurethane polymer takes part, via azomethine formation during and/or after film formation. There is no teaching or suggestion regarding breathability properties of the composition or the importance of amounts and length of side-chain and main-chain polyoxyethylene in achieving both breathability and other suitable polyurethane properties. In addition, Applicants' breathable polyurethanes do not contain hydrazine functional groups or hydrazone functional groups.
U.S. Pat. No. 4,190,566 relates to non-ionic, water-dispersible polyurethanes having a substantially linear molecular structure and lateral polyalkylene oxide chains having about 3 to 30% by weight of lateral polyalkylene oxide polyether chains. The chains consist of about 40-95% ethylene oxide units and 5-60% certain other alkylene oxide units selected from the group consisting of propylene oxide, butylene oxide and styrene oxide). Coatings are among the many uses listed, but there is no teaching regarding breathability properties of the composition or the importance of amounts and length of side-chain and main-chain polyoxyethylene in achieving both breathability and other suitable polyurethane properties.
U.S. Pat. No. 4,092,286 relates to water-dispersible polyurethane elastomers having a substantially linear molecular structure, characterized by (a) lateral polyalkylene oxide units of from about 0.5 to 10% by weight, based on the polyurethane as a whole and (b) a content of ═N+═, —COO− or —SO3− groups of from about 0.1 to 15 milliequivalents per 100 g. Coatings are among the many uses listed, but there is no teaching or suggestion regarding breathability properties of the composition or the importance of amounts and length of side-chain and main-chain polyoxyethylene in achieving both breathability and other suitable polyurethane properties.
A waterborne polyurethane dispersion is desired that can be used to produce films, coatings and other compositions having improved moisture vapor transmission rates and other improved properties compared to polyurethanes of the prior art.